20 R/F CONVERTER (RFC)
S1C31D50/D51 TECHNICAL MANUAL
Seiko Epson Corporation
20-1
(Rev. 2.00)
20 R/F Converter (RFC)
20.1 Overview
The RFC is a CR oscillation type A/D converter (R/F converter).
The features of the RFC are listed below.
• Converts the sensor resistance into a digital value by performing CR oscillation and counting the oscillation
clock.
• Achieves high-precision measurement system with low errors by oscillating the reference resistor and the sensor
in the same conditions to obtain the difference between them.
• Includes a 24-bit measurement counter to count the oscillation clocks.
• Includes a 24-bit time base counter to count the internal clock for equalizing the measurement time between the
reference resistor and the sensor.
• Supports DC bias resistive sensors and AC bias resistive sensors.
(Note: See the table below.)
(A thermometer/hygrometer can be easily implemented by connecting a thermistor or a humidity sensor and a
few passive elements (resistor and capacitor).)
• Allows measurement (counting) by inputting external clocks.
• Provides an output and continuous oscillation function for monitoring the oscillation frequency.
• Can generate reference oscillation completion, sensor (A and B) oscillation completion, measurement counter
overflow error, and time base counter overflow error interrupts.
Figure 20.1.1 shows the RFC configuration.
Table 20.1.1 RFC Channel Configuration of S1C31D50/D51
Item
48-pin package
64-pin package
80-pin package
100-pin package
Number of channels
1 channel (Ch.0)
Note: DC oscillation mode for resistive sensor measurements can only be used.
Inter
nal data
bu
s
RFC Ch.n
Counter
control circuit
CONEN
EVTEN
SMODE[1:0]
Time base counter
TC[23:0]
Measurement counter
MC[23:0]
CLKSRC[1:0]
CLKDIV[1:0]
Clock generator
DBRUN
MODEN
RFCLKMD
TCCLK
RFCLKOn
RFINn
REFn
SENAn
SENBn
Interrupt
control circuit
CR oscillation
control circuit
SSENB
SSENA
SREF
Oscillation
circuit
OVTCIE
OVMCIE
ESENBIE
ESENAIE
EREFIE
OVTCIF
OVMCIF
ESENBIF
ESENAIF
EREFIF
CPU core
1/2
Figure 20.1.1 RFC Configuration